A fairly common type of
mouth allergy is called oral allergy syndrome. Swelling or itching of lips, mouth tongue or throat follows
immediately after contact with certain foods. It occurs in hay fever sufferers
and also in people who are allergic to rubber latex. It is caused by a true allergy to certain fresh fruits, nuts and raw
vegetables. Reactions to the same
foods when cooked are less likely but can sometimes occur.
In most cases there is only a low risk
of progression to
a severe reaction. In a few people, symptoms in the mouth or
throat may be caused by other foods such as nuts, shrimp or egg, and for these the risk of
progression to a more severe generalised reaction is greater. People with
oral allergy caused by fruits or vegetables often have an associated allergy to certain
pollens, and may get hay fever when these pollens are in season.
is the commonest form of oral allergy syndrome. A number of pollen allergies may be connected with
the condition, although the commonest is birch pollen. It has been
estimated that as many as 75% of birch-allergic patients may be affected
by the mildest form, a sensation in the lips or tongue after eating raw
apples. However, many sufferers do not realise that they have an allergic problem. Other pollens involved include grass pollen
and certain weed (e.g. mugwort) pollens.
Adults appear to develop this condition more often
than children, local reaction to fruits and vegetables being the most frequently encountered
kind of food allergy in sufferers over the age of ten. Children appear more likely to
suffer a more widespread kind of allergy (e.g. rash, vomiting or wheeze) as a response to
foods such as egg, nuts or seafood to which they are allergic and in them, the oral allergy
syndrome and reactions to fruits or raw vegetables is less common.
Redness, swelling and itching, with or without
rash (blotchy, pimply or even blistering) of lips, tongue, inside of mouth and soft
Occasionally itchy swelling of the throat may
Symptoms in the oesophagus (gullet) or stomach
include pain and discomfort, heartburn, nausea and even vomiting.
General symptoms such as urticaria (nettle rash)
rhinitis and asthma may occur minutes or an hour or two later, particularly if the
sufferer ignores the local symptoms and eats all of the culprit food.
This is another type of oral allergy
syndrome. People who react to a particular group of foods may also be
allergic to latex, a condition known as latex-food
The cause is the presence of similar proteins
present in the latex and also in the raw fruits concerned. Latex is the
substance collected from rubber trees out of which rubber is made.
Latex balloons, rubber gloves, elastic and certain medical devices may
cause symptoms after skin or mouth contact, or sometimes asthma and
rhinitis if latex dust (for example in the powder from rubber gloves) is
inhaled. General aspects of allergy to rubber
are discussed elsewhere.
list of the foods that may cause symptoms to sufferers of both latex-fruit
syndrome and pollen-fruit syndrome is given below.
likely culprits are shown in bold type:
apple, apricot, carrot, celery, cherry, coriander, fennel,
kiwi, nectarine, parsley, parsnip, peach, pear, peppers,
potato, prune, tomato, walnut - occasional patients also
react to raw legumes (e.g. pea, green bean, mange tout)
peanut, tomato, watermelon
apple, apricot, avocado, banana, raw carrot, raw
celery, chestnut, cherry, dill, fig, ginger, kiwi,
mango, melon, oregano, papaya, passion fruit, peach, pear, plum, raw
potato, sage, raw tomato
reactions to fruit and vegetables are not always
related to pollen or latex. In some cases, there is
a primary allergy to the food itself. These
reactions may be more severe.
in the mouth can also be caused by primary food
allergy (i.e. it is not secondary to pollen or latex
allergy). Examples are peanuts, tree nuts, egg
white, prawns and fish. Primary food allergy has the
potential to be much more serious.
reaction to a food should be investigated by your
GP. Mild symptoms should not be ignored. The GP
should be able to decide what type of food allergy
you have and whether you need to be referred to an
The correct identification and avoidance of the
culprit food or foods must be the main aim. Previous experience of what has happened when
eating certain foods is the most important evidence. Some foods seem only to cause
problems when eaten in the raw state (often the case with carrot and apple) and eating the
foods when cooked causes no problem. Skin and blood tests can help to confirm the
diagnosis. It does not follow that all the foods of a particular group will cause
trouble for someone who reacts to one or two of them. Unless you are advised otherwise,
only the foods that have caused symptoms in the past should be avoided.
In addition, you should stay alert to the possibility
that further sensitivities to other foods in the same group might develop in the future.
Once you are sure that a particular food is causing symptoms, (and especially if a skin or
blood test confirms the allergy) it is better to exclude it in future.
In an occasional case where it is considered that
there may be a small risk of severe or generalised reaction a sufferer may be advised to carry
adrenaline by injection as a precaution. In other cases, especially where the throat is
involved, an adrenaline aerosol spray may be advised.
Most sufferers have mild symptoms and can generally
be reassured that their condition is never likely to become severe, although it is unlikely
that they will ever grow out of it. Desensitisation treatment for this condition is not
available at the present time, although it is possible that this form of treatment might
become available in the future.